O.S. Engines 21XZ-M - Manual (Page 12)

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PRECAUTIONS
When starting the engine, with the hull out
off the water and no load on the engine,
even below half throttle, the engine can
over-rev. Prolonged running at higher
throttle settings can result in seizure of the
connecting rod and crankpin. Never run the
engine with the throttle above the starting
setting with the hull out of the water and no
load on the engine. Next, disconnect the glowplug battery and
try running the hull on the water. If the
engine stalls, open the throttle fractionally,
but try to keep the engine running as rich as
possible: if it stops because of being
excessively over-rich, close the Needle-
Valve 30˚ and try again.
Run the hull on the water until one tank of fuel
has been consumed, then close the Needle-
Valve one click and run the hull for another full
tank of fuel. Repeat this procedure until 5 more
tanks of fuel have been consumed, during
which time the throttle may be opened for brief
bursts of increased power.
If the engine stops at medium speeds, close
the Mixture Screw 10˚.
23
Needle
The position of the needle-valve
when starting the engine.
Close the needle-valve approx.
30˚ after running the hull for one full
tank of fuel. Repeat this procedure
several times.
If the engine should need to be
disassembled (e.g. for cleaning or minor
parts replacement) it is advisable to return
the Needle-Valve to the original rich,
starting setting and check whether further
running-in time is required before the car is
raced again. In the event of any major
working parts(e,g, piston/cylinder liner
assembly) being replaced, the complete
running-in should be repeated.
Remember!
Warning!
Do not touch rotating parts, engine and si-
lencer when stopping the engine as they
become very hot, and contact with them
may result in a serious burn.
Throttle Trim
Throttle Stick
TO STOP THE ENGINE
Lower the throttle trim and/or throttle stick on
the transmitter.